I don't know if it's of any use to you guys but last year I wanted to convert a map from Shadow Warrior (Build) to Kingpin (Quake II), but couldn't manage to find a proper geometry converter (many abandoned projects and cumbersome/unreliable programs). Because I had a lot of free time on my hands and I enjoy coding silly tools, I decided to write my own.

Over time, the project has been entirely rewritten three times and is now able to convert the static geometry of any game based on the Build-engine or the Doom engine (and kind of produce a half-assed job with Dark Forces). It can also parse information straight from resource files (that includes encrypted RFFs), and convert textures as needed: TGA, MIP, WAL (Quake II), WAD2 (Quake) or WAD3. The output is either in Quake or Quake II .MAP format and provides a rough preview of the texturing (there's no alignment or scaling)... as for the geometry, see for yourself:

Since it's a very niche utility and it is unlikely to be caught by search engines, I thought I'd drop a line here. You can download sectorCut (that's the name of the thing) here (183Kb) and check the changelog and some more screenshots in this thread on Kingpin Forever (I'm posting the link to that thread because I'm more likely to hang there than here).

I'm not expecting tons of feedbacks, but hey! Maybe this thing will be useful to someone.
Best of luck to the survivors.